i would wait till tomorrow morning i think. but im not too sure, lol!
im already thinking about when DD goes for hers in September (4yo ones) i have never taken any of my kids for any of their needles (i have a bad phobia of needles, and have a tendacy to pass out upon sight of one lol) but im thinking im gonna have to be the one to take her in, cos she will know and understand this time, and will want me to hold her hand!
maybe if u did mention it today, u could make a lil game of it. tell him whats gonna happen, and say it should oly hurt this muc, and do a very slight lil pinch! and then tickle him or something.
maybe tell him afterwards you can go for an ice cream/play in the park/something he enjoys for being so brave?
i will be getting soem emla cream from the chemist before hand so the area is numb for DD, so their shouldnt be much pain, if nay at all, and wil keep her distracted so she cant see it (and so i cant see it) maybe close her eyes and *** to ten slowly!